Is it valid to enter into a forward sale for a garment based on a specific torn rag ('Khirqah) brought forth by the buyer?

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A forward sale for a garment based on a specific torn rag presented by the buyer is not permissible. This introduces uncertainty (Gharar) because the rag might perish, and there is no necessity for such a specific reference. This invalidity is analogous to stipulating a specific measure or a specific scale.